WO 95/20058 discloses a cooling cover with air nozzles arranged exclusively in the bottom third of its height. The coils are usually stacked on top of each other, being separated by convector plates. Volumetric flows through the convector ducts are significantly larger for the bottom coils in the stack than for the top coils. Consequently, coils lying at the bottom are at an advantage during cooling, while coils lying at the top are at a disadvantage. This is exacerbated by the fact that cooling occurs only in the bottom region. The cooling process cannot be ended until the temperature in the core of the top coil falls below the maximum temperature set for the end of cooling, which means that the cooling process takes fairly long.